Use of arsenic compounds for treatment of pain and inflammation

ABSTRACT

The present invention relates to the use of arsenic compounds such as sodium meta arsenite (NaAsO 2 ), arsenic trioxide (As 2 O 3 ), and arsenic hexoxide (As 4 O 6 ) or combinations thereof, for the treatment of painful, hyperalgesic and/or inflammatory conditions. The present invention also relates to compositions containing the above arsenic compounds for use in the treatment of pain, inflammation and immunological and autoimmune diseases and disorders.

This application claims priority to provisional application Ser. No.60/899,007, filed Feb. 2, 2007, incorporated herein in its entirety byreference thereto.

FIELD OF THE INVENTION

This invention relates to methods and compositions for treating pain andinflammation, as well as treating autoimmune and immunological disordersusing arsenic compounds. More particularly, the methods and compositionsof the present invention relate to the use of sodium meta arsenite(NaAsO₂), arsenic trioxide (As₂O₃), and/or arsenic hexoxide (As₄O₆) orsalts thereof, to treat pain, inflammation, and autoimmune andimmunological disorders.

BACKGROUND OF THE INVENTION

Pain perception, or nociception, is mediated by the peripheral terminalsof a group of specialized sensory neurons, termed nociceptors. A widevariety of physical and chemical stimuli induce activation of suchneurons in mammals, leading to recognition of a potentially harmfulstimulus. Inappropriate or excessive activation of nociceptors, however,can result in debilitating acute or chronic pain.

Generally pain is experienced when the free nerve endings whichconstitute the pain receptors in the skin as well as in certain internaltissues are subjected to mechanical, thermal, chemical or other noxiousstimuli. The pain receptors can transmit signals along afferent neuronsinto the central nervous system and thence to the brain.

The causes of pain can include inflammation, physical injury, infectiousdisease, chemical or anoxic injury, muscle spasm and the onset of aneuropathic event or syndrome. Ineffectively treated pain can bedevastating to the person experiencing it by limiting function, reducingmobility, complicating sleep, and dramatically interfering with thequality of life.

Inflammation is a physiological condition characterized in the acuteform by the classical signs of pain, heat, redness, swelling and loss offunction. Inflammatory pain can occur when tissue is damaged. Forexample, physical, chemical, and thermal events, surgery, infection andautoimmune diseases can cause tissue damage and inflammation. When atissue is damaged, a host of endogenous pain-inducing substances, forexample bradykinin and histamine can be released from the injuredtissue. The pain-inducing substances can bind to receptors on thesensory nerve terminals and thereby initiate afferent pain signals.

Additionally, pain-inducing substances can be released from nociceptiveafferent terminals, and neuropeptides released from sensory terminalscan accentuate an inflammatory response. Thus, during inflammation therecan be a sprouting of peptidergic peripheral fibers and an increasedcontent of peptide, with many fibers showing a coexistence of substanceP (SP) and calcitonin gene related peptide (CGRP). Substance P caninduce contraction of endothelia cells, which in turn causes plasmaextravasation to allow other substances (bradykinin, AIP, histamine) togain access to the cite of injury and the afferent nerve terminals.Substance P release by the sensory nerve terminal can also degranulatemast cells. This process is thought to be an important factor inneurogenic inflammation due to the release of inflammatory mediatorssuch as histamine and serotonin and the release of proteolytic enzymeswhich catalyze the production of bradykinin. CGRP apparently does notproduce plasma extravasation, but is a powerful vasodilator and alsoacts synergistically with SP and other inflammatory mediators to enhanceplasma extravasation. All the above listed inflammatory mediators caneither sensitize nociceptors or produce pain. Hence, inhibition of theinflammatory mediators' release and/or activity can be useful in thetreatment of common inflammatory diseases such as, for example, asthma,arthritis, dermatitis, rhinitis, cystitis, gingivitis,thrombo-phlelitis, glaucoma, astro-intestinal diseases or migraine.

Although inflammatory pain is generally reversible and subsides when theinjured tissue has been repaired or the pain inducing stimulus removed,present methods for treating chronic inflammatory pain have manydrawbacks and deficiencies. Thus, the typical oral, parenteral ortopical administration of an analgesic drug to treat the symptoms ofpain, for example, an antibiotic to treat inflammatory pain causingfactors, can result in widespread systemic distribution of the drug andundesirable side effects. Additionally, current therapy for inflammatorypain suffers from short duration of drug efficacy, which necessitatesfrequent drug re-administration with possible resulting increasing drugtolerance and resistance, antibody development and/or drug dependenceand addiction, all of which are unsatisfactory. Furthermore, frequentdrug administration increases the expense of the regimen to the patientand can require the patient to remember to adhere to a dosing schedule.

Examples of treatments for inflammation and muscle pain includenon-steroidal anti-inflammatory drugs (NSAIDs), including aspirin andibuprofen; and opioids, such as morphine.

NSAIDs alleviate pain by inhibiting the production of prostaglandinsreleased by damaged tissues. Prostaglandins have been shown to beperipheral mediators of pain and inflammation, as in arthritic diseases,and a reduction in their concentration provides relief to patients. Ithas been suggested that prostaglandins are involved in the mediation ofpain in the spinal cord and the brain, which may explain the analgesiceffects of NSAIDS in some pain states that do not involve inflammationor peripheral tissue damage. However, prostaglandins are only one ofseveral mediators of pain. As such, NSAIDs have a ceiling of activityabove which increasing doses do not give more pain relief.

Furthermore, NSAIDs have side effects that limit their usefulness. Forexample, they can cause irritation of the gastrointestinal tract andprolonged use may lead to the development of extensive ulceration of thegut. This is particularly true in elderly patients who frequently useNSAIDs for their arthritis conditions.

The therapeutic actions of opioids are on the central nervous systemincluding the brain and spinal cord. Opioids inhibit the efficiency ofneurotransmission between the primary sensory afferents (principallyC-fibers) and the projection neurons. They achieve this by causing aprolonged hyperpolarization of both elements of these synapses. The useof opioids is effective in alleviating most types of acute pain andchronic pain caused by the malignant tumors. There are, however, anumber of chronic malignant pain conditions that are partly orcompletely refractory to opioid analgesia, particularly those thatinvolve nerve compression, e.g. by tumor formation and growth.Unfortunately opioids also have unwanted side-effects includingdepression of the respiratory system, constipation, and psychoactiveeffects including sedation, euphoria and drug dependency. These sideeffects occur at doses similar to those that produce analgesia and,therefore, limit the doses that can be given to patients. Additionally,opioids such as morphine and heroin are well-known drugs of abuse thatoften lead to rapid increase in drug tolerance and physical dependence.With the development of tolerance, the dose and frequency of drugrequired to produce the same analgesic effect increases with time. Thismay lead to a condition in which the doses required to alleviate thechronic unremitting pain can be life-threatening due to previouslymentioned side-effects. As used herein, the term “chronic” means painlasting for one month duration or longer. “Acute pain” is defined aspain of shorter duration than chronic pain and of high intensity.

Although pain arising from inflammation and muscle spasm can beinitiated by mechanical or chemical stimulation of the primary sensoryneuron free terminal, neuropathic pain does not require an initialstimulus to the peripheral, free nerve terminal. Neuropathic pain is apersistent or chronic pain syndrome that can result from damage to thenervous system, the peripheral nerves, the dorsal root ganglion, dorsalroot, or to the central nervous system.

Neuropathic pain involves pain signal transmission in the absence ofstimulus, and typically results from damage to the nervous system. Inmost instances, such pain is thought to occur because of sensitizationin the peripheral and central nervous systems following initial damageto the peripheral system (e.g., via direct injury or systemic disease).Neuropathic pain is typically burning, shooting and unrelenting in itsintensity and can sometimes be more debilitating that the initial injuryor disease process that induced it.

Existing treatments for neuropathic pain are largely ineffective.Opiates, such as morphine, are potent analgesics, but their usefulnessis limited because of adverse side effects mentioned earlier, such asrapid development of drug tolerance, physical addictiveness andwithdrawal properties, as well as respiratory depression, mental statuschanges, and decreased intestinal motility with concomitantconstipation, nausea, vomiting, and alterations in the endocrine andautonomic nervous systems. In addition, neuropathic pain is frequentlynon-responsive or only partially responsive to conventional opioidanalgesic regimens. Treatments employing the N-methyl-D-aspartateantagonist ketamine or the alpha(2)-adrenergic agonist clonidine canreduce acute or chronic pain, and permit a reduction in opioidconsumption, but these agents are often poorly tolerated due tosignificant side effects.

Neuropathic pain syndromes include allodynia, various neuralgias such aspost herpetic neuralgia and trigeminal neuralgia, phantom pain, andcomplex regional pain syndromes, such as reflex sympathetic dystrophyand causalgia. Causalgia is often characterized by spontaneous burningpain combined with hyperalgesia and allodynia.

Unfortunately, there is no existing method for adequately, predictablyand specifically treating established neuropathic pain (Woolf C. et al.,Neuropathic Pain: A etiology, Symptoms, Mechanisms, and Management,Lancet 1999; 353: 1959-64) as present treatment methods for neuropathicpain consists of merely trying to help the patient cope throughpsychological or occupational therapy, rather than by reducing oreliminating the pain experienced.

Therefore, there remains a need for an improved method or compound forthe treatment of unremitting chronic and acute pain, includinginflammatory pain. There is also a need for improved methods and agentsfor treatment of immunological and autoimmune diseases and conditions.This is achieved by administration of arsenic compounds, in accordancewith this disclosure.

SUMMARY OF THE INVENTION

The present invention addresses the limitations noted for the backgroundart and provides new methods for reducing inflammation and/or chronic,acute, and/or and/or pain. The present invention is based, in part, onthe discovery and demonstration that arsenic compounds such as sodiummeta arsenite (NaAsO₂), arsenic trioxide (As₂O₃), and/or arsenichexoxide (As₄O₆) or salts thereof, may be used to reduce inflammationand pain.

This disclosure, according to an aspect of the invention, providesmethods for treating a mammal (e.g., a human) suffering from chronic,and/or acute. In accordance with certain embodiments of this aspect ofthe invention, the disclosure provides methods for the use of arseniccompounds, preferably sodium meta arsenite (NaAsO₂), arsenic trioxide(As₂O₃), and/or arsenic hexoxide (As₄O₆) or salts thereof, to treat orprevent pain including, for example, visceral pain (such aspancreatitis), cancer related pain (such as metastatic cancer), centralpain syndromes (such as the pain caused by stroke), postsurgical painsyndromes (e.g., postmastectomy syndrome), bone and joint pain(osteoarthritis), spine pain (e.g., acute and chronic low back pain),myofascial pain (muscular injury), postoperative, perioperative pain andpreemptive analgesia, chronic pain, dysmenorrhea, as well as painassociated with angina, and inflammatory pain of varied origins (e.g.,asthma, osteoarthritis, rheumatoid arthritis).

In an exemplary embodiment, the invention provides the use of sodiummeta arsenite (NaAsO₂), arsenic trioxide (As₂O₃), and/or arsenichexoxide (As₄O₆) or salts thereof, in the preparation of topical, oralor parenteral composition to treat acute and chronic hyperalgesia.

Within an aspect of the invention is provided a method for treatinginflammation, comprising administering a therapeutically sufficientamount of an inorganic arsenic compound, e.g., sodium meta-arsenite(NaAsO2), arsenic trioxide (As₂O₃); and/or arsenic hexoxide (As4O6) to amammal, wherein administration of the compound results in a clinicallysignificant improvement in the inflammatory condition of the mammal.Within an embodiment of the invention, the clinically significantimprovement in the inflammatory condition includes one or more of thefollowing:

a) a decrease or inhibition in pain; b) a decrease or inhibition inswelling; c) a decrease or inhibition in redness; d) a decrease orinhibition in temperature of an affected tissue; and e) and a decreaseor inhibition in loss of function.

It is theorized, but not relied on for the purpose of this invention,that histamine, cytokinins and other polypeptides release is likely tooccur in inflammatory conditions, such as in lungs of asthma patients.Accordingly, in an embodiment the methods of the invention involve localor systemic administration of sodium meta-arsenite to treat inflammationand/or tissue damage displayed in, for example, asthmatic airways andcancer related necrosis.

In another embodiment, the methods of the invention provide localadministration of sodium meta-arsenite, arsenic trioxide and/or arsenichexoxide to treat inflammation at a damaged-tissue site on anindividual.

In other embodiments, the invention provides methods of treating painand/or tissue damage associated with inflammation, e.g., tissue fibrosisin cancer related or autoimmune induced disease. Examples of immune andautoimmune diseases that may be treated by the present methods includeimmune and autoimmune disease of the endocrine, neuromuscular,connective tissue, cardiopulmonary, skeletal and gastrointestinalsystems. In particular, the arsenic compounds of the invention may beused to treat autoimmune disorders and immunologically mediateddisorders such as multiple sclerosis and other immune relatedconditions.

In another embodiment, inflammation and pain caused by infectiousdisease, including bacterial, viral, parasitic infections are treated bythe methods of the invention.

The methods of the invention comprise administering a therapeuticallyeffective amount of sodium meta arsenite, arsenic trioxide and/orarsenic hexoxide, as appropriate. In preferred embodiments, thetherapeutic amount is in the range of from about 10 μg to about 200 mg,preferably in divided doses which are administered parenterally,intrathecally, orally, via inhalation or topically. A preferred totaldaily dose is from about 0.5 mg to about 70 mg; most preferably about 10mg/kg.

It is further theorized, but not relied on for the purpose of thisinvention, that sodium meta-arsenite, arsenic trioxide and/or arsenichexoxide inhibits and/or depletes leucocytes and lymphocytes that areinvolved in producing autoimmune antibodies and damaging tissues.Accordingly, in an exemplary embodiment, the methods of the inventionprovide local or systemic administration of sodium meta-arsenite,arsenic trioxide and/or arsenic hexoxide to treat autoimmune inducedinflammations and/or tissue damage.

The term “hyperalgesia” or “hyperalgesic sensation” as used hereinrefers to an extreme sensitivity to pain, which in one form is caused bydamage to nociceptors in the body's soft tissues. Hyperalgesia can beexperienced in focal, discrete areas, or as a more diffuse, body-wideform. Conditioning studies have established that it is possible toexperience a learned hyperalgesia of the latter, diffuse form. The focalform is typically associated with injury, and is divided into twosubtypes: Primary hyperalgesia describes pain sensitivity that occursdirectly in the damaged tissues. Secondary hyperalgesia describes painsensitivity that occurs in surrounding undamaged tissues.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph of data obtained through histopathologicalassessment of bone necrosis and inflammation caused by tumor burden inrats treated with sodium meta arsenite.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides methods of treating a mammal (e.g., a human)suffering from pain and/or inflammatory diseases or conditions. Inparticular embodiments, such methods include local or systemicadministration of arsenic compounds, preferably sodium meta arsenite(NaAsO₂), arsenic trioxide (As₂O₃), and/or arsenic hexoxide (As₄O₆) orsalts thereof, to treat inflammation and acute and/or chronic pain.

In certain embodiments, sodium meta arsenite (NaAsO₂), arsenic trioxide(As₂O₃), and/or arsenic hexoxide (As₄O₆) or salts thereof are used totreat or prevent pain including, for example, visceral pain (such aspancreatitis, interstitial cystitis, renal colic, prostatitis, chronicpelvic pain) cancer related pain, the “dynias”, e.g., vulvodynia,phantom limb pain, root avulsions, radiculopathy, painful traumaticmononeuropathy, painful entrapment neuropathy, carpal tunnel syndrome,ulnar neuropathy, tarsal tunnel syndrome, painful diabetic neuropathy,painful polyneuropathy, trigeminal neuralgia), central pain syndromes(potentially caused by virtually any lesion at any level of the nervoussystem including but not limited to stroke, multiple sclerosis, spinalcord injury), and post-surgical pain syndromes (e.g., post-mastectomysyndrome, post-thoracotomy syndrome, stump pain), bone and joint pain(osteoarthritis), spinal pain (e.g., acute and chronic low back pain,neck pain, spinal stenosis), shoulder pain, repetitive motion pain,acute pain such as dental pain, sore throat, cancer pain, myofascialpain (muscular injury, fibromyalgia), postoperative, perioperative painand preemptive analgesia (including but not limited to general surgery,orthopedic, and gynecological), chronic pain, dysmenorrhea (primary andsecondary), as well as pain associated with angina, and inflammatorypain of varied origins including immunological reactions and autoimmunediseases (e.g., osteoarthritis, rheumatoid arthritis, rheumatic disease,teno-synovitis and gout, ankylosing spondylitis, bursitis, Lupus).

Arsenic compounds of the present invention may also be used for thetreatment of headache including cluster headache, migraine includingprophylactic and acute use, stroke, closed head trauma, cancer, sepsis,gingivitis, osteoporosis, benign prostatic hyperplasia and hyperactivebladder.

The skilled artisan will appreciate that pain is a heterogeneousdisorder. In the methods and compositions according to the invention,the term “pain” shall refer to all types of pain, including acute andpersistent pain. Preferably, the term shall refer to persistent pains,such as, but not limited to, diabetic neuropathy, fibromyalgia, painassociated with somatoform disorders, arthritic pain, cancer pain, neckpain, shoulder pain, back pain, cluster headaches, tension-typeheadache, migraine, herpes neuralgia, phantom limb pain, central pain,dental pain, NSAID-resistant pain, visceral pain, surgical pain,post-operative pain, bone injury pain, pain during labor and delivery,pain resulting from burns, including sunburn, post-partum pain, anginapain, and genitourinary tract-related pain including cystitis. The termpersistent pain shall also preferably refer to nociceptive pain ornociception.

Within another aspect of the invention is provided a method for treatinginflammation, comprising administering a therapeutically sufficientamount of an inorganic arsenic compound, e.g., sodium meta-arsenite(NaAsO2) to a mammal, wherein administration of the compound results ina clinically significant improvement in the inflammatory condition ofthe mammal. Within an embodiment of the invention, the clinicallysignificant improvement in the inflammatory condition includes one ormore of the following: a) a decrease or inhibition in pain; b) adecrease or inhibition in swelling; c) a decrease or inhibition inredness; d) a decrease or inhibition in heat; and e) and a decrease orinhibition in loss of function.

Asthma is a disease of the airways that contains elements of bothinflammation and broncho constriction. Treatment regimens for asthma arebased on the severity of the condition. Mild cases are either untreatedor are only treated with inhaled beta (B)-agonists which affect thebronchoconstriction element, whereas patients with more severe asthmatypically are treated regularly with inhaled corticosteroids which to alarge extent are anti inflammatory in their nature.

In certain other embodiments of the invention, sodium meta-arsenite isused to treat or prevent hyperreactive airways and to treat or preventinflammatory events associated with airways disease, e.g., asthmaincluding allergic asthma (atopic or non-atopic), as well asexercise-induced bronchoconstriction, occupational asthma, viral- orbacterial exacerbation of asthma, other non-allergic asthmas and“wheezy-infant syndrome.”

Chronic obstructive pulmonary disease (COPD) is another common diseasewith inflammatory and bronchoconstrictive components. The disease ispotentially lethal, and the morbidity and mortality from the conditionis considerable. At present, there is no known pharmacological treatmentcapable of changing the course of the disease.

The arsenic compounds of the invention, e.g., sodium meta arsenite inaccordance with an exemplary embodiment of the present invention, mayalso be used to treat chronic obstructive pulmonary disease includingemphysema adult respiratory distress syndrome, bronchitis, pneumonia,allergic rhinitis (seasonal and perennial), and vasomotor rhinitis. Itmay also be effective against pneumoconiosis, including aluminosis,anthracosis, asbestosis, chalicosis, ptilosis, siderosis, silicosis,tabacosis, and byssinosis.

Furthermore, the arsenic compounds of the invention, such as sodium metaarsenite, in accordance with other embodiments of the present invention,may be used for the treatment of inflammatory bowel disease includingCrohn's disease and ulcerative colitis, irritable bowel syndrome,pancreatitis, nephritis, cystitis (interstitial cystitis), uveitis,inflammatory skin disorders such as psoriasis and eczema, rheumatoidarthritis and edema resulting from trauma associated with burns, sprainsor fracture, cerebral edema and angioedema. It may be used to treatdiabetic vasculopathy, diabetic neuropathy, diabetic retinopathy, postcapillary resistance or diabetic symptoms associated with insulitis(e.g. hyperglycemia, diuresis, proteinuria and increased nitrite andkallikrein urinary excretion). The arsenic compounds of the invention,preferably, sodium meta arsenite, may be used as smooth muscle relaxantsfor the treatment of spasm of the gastrointestinal tract or uterus.Additionally, they may be effective against liver disease, multiplesclerosis, cardiovascular disease, e.g. atherosclerosis, congestiveheart failure, myocardial infarct; neurodegenerative diseases, ea.Parkinson's and Alzheimer's disease, epilepsy, septic shock e.g. asanti-hypovolemic and/or anti-hypotensive agents.

In another embodiment, the arsenic compounds of the invention are usedto prevent and/or treat inflammatory liver disease, or multiplesclerosis.

Another embodiment provides, in accordance with the invention, the useof arsenic compounds, in particular sodium meta-arsenite, in a topicalcomposition to treat, reduce, or prevent local inflammation. In anembodiment, the arsenic compound, e.g., sodium meta-arsenite isadministered to a mammal to reduce or prevent histamine release.

In other embodiments, in accordance with the present invention, sodiummeta-arsenite or other arsenic compound(s) of the invention isadministered to a mammal (e.g., a human) to treat or reduce inflammationsymptoms associated with immune-mediated and/or autoimmune diseases suchas, for example, systemic lupus erythematosus (SLE), autoimmunerheumatoid arthritis (RA), systemic vasculitis; insulin-dependentdiabetes mellitus (IDDM; type I diabetes, inflammatory bowel disease(IBD), graft versus-host disease (GVHD), celiac disease, autoimmunethyroid disease, Sjögren's syndrome, autoimmune gastritis, ulcerativecolitis; Crohn's disease; autoimmune hepatitis, primary biliarycirrhosis; primary sclerosing cholangitis; cutaneous autoimmunediseases, autoimmune dilated cardiomyopathy, multiple sclerosis (MS),myasthenia gravis (MG), vasculitis (e.g., Takayasu's arteritis andWegener's granulomatosis), autoimmune diseases of the muscle, autoimmuneneuromuscular disorders, such as ankylosing spondylitis, multiplesclerosis, and acute disseminated encephalitis; immune mediatedneuropathies; autoimmune diseases of testis, autoimmune ovarian disease,autoimmune uveitis, Graves' disease, psoriasis, ankylosing spondylitis,Addison disease, Hashimoto thyroiditis, idiopathic thrombocytopenicpurpura, autoimmune lung disease such as Wegener's disease andChurg-Strauss syndrome; immunologic lung diseases such as asthma,infiltrative lung disease, hypersensitivity lung disease andsarcoidosis; dermatomyosis including scleroderma and polymyosis; andvitiligo.

The methods of the invention are expected to slow or stop theprogression of inflammation, improve at least some symptoms,functioning, and/or increase survival and recovery.

According to certain other aspect of the present invention, sodium metaarsenite (NaAsO₂), arsenic trioxide (As₂O₃), and/or arsenic hexoxide(As₄O₆) or salts thereof, may be used to inhibit and or depleteleucocytes or lymphocytes and their secretions, which are associated tothe onset of autoimmune disorders in a human. According to oneembodiment of this aspect of the invention, administration of sodiummeta-arsenite can result in a reduction in the levels of autoantibodies, B cells producing auto antibodies, and/or auto reactive Tcells. The reduction in any of these cell types or their secretions canbe, for example, at least 10%, 20%, 30%, 50%, 70%, or more as comparedto pretreatment levels.

In accordance with the present invention, arsenic compounds of theinvention can be used alone or in combination with other known painand/or anti-inflammatory medications such as, for example, NSAIDs.Combinations of arsenic compounds are also contemplated.

Animal models of the above-mentioned diseases and conditions aregenerally known in the art, and may be suitable for evaluating compoundsof the present invention for their potential utilities. Finally,compounds of the present invention are also useful as research tools (invivo and in vitro).

The methods of the invention can be used to treat a mammal that has painand/or inflammation, e.g., rheumatoid arthritis-associated pain orasthma-associated inflammation. Examples of mammals include humans orother primates (e.g., chimpanzees), rodents (e.g., mice, rat, or guineapigs), rabbits, cat, dogs, horses, cows, and pigs. In some of thesubjects afflicted, the treatment is expected to result in inhibitingthe progression of, and improvement in pain and/or inflammationsymptoms.

Method of Administration

Any suitable mode of administration may be used in accordance with thepresent invention including, but not limited to parenteraladministration such as intravenous, subcutaneous, intramuscular andintrathecal administration; oral, intranasal, rectal or vaginaladministration may also be used; directly into the tumor; transdermalpatches; implant devices (particularly for slow release); inhalers,long-acting depot administration, and finally, topical administrationmay be used. The mode of administration will vary according to the typeof arsenic compound being used and the disease to be treated.

The pharmaceutical compositions to be used may be in the form of sterilephysiologically acceptable (aqueous or organic) solutions, colloidalsuspensions, creams, ointments, pastes, capsules, caplets, tablets andcachets. The pharmaceutical compositions comprising arsenic compounds ofthe invention can be contained in sealed sterile glass containers and/orampoules. Further, the active ingredient may be micro-encapsulated,encapsulated in a liposome, noisome or lipofoam alone or in conjunctionwith targeting antibodies. It should be recognized that delayed slow orsustained release forms of administration are also included.

Formulation

The arsenic compounds of the invention may be formulated intopharmaceutical preparations for administration to mammals for treatmentof pain and inflammation.

For oral administration, the pharmaceutical preparation may be in liquidform, for example, solutions, syrups or suspensions, or may be presentedas a drug product for reconstitution with water or other suitablevehicle before use. Such liquid preparations may be prepared byconventional means with pharmaceutically acceptable additives such assuspending agents (e.g., sorbitol syrup, cellulose derivatives orhydrogenated edible fats); emulsifying agents (e.g., lecithin oracacia); non-aqueous vehicles (e.g., almond oil, oily esters, orfractionated vegetable oils); and preservatives (e.g., methyl orpropyl-p-hydroxybenzoates or sorbic acid). The pharmaceuticalcompositions may take the form of, for example, tablets or capsulesprepared by conventional means with pharmaceutically acceptableexcipients such as binding agents (e.g., pregelatinized maize starch,polyvinyl pyrrolidone or hydroxypropyl methylcellulose); fillers (e.g.,lactose, microcrystalline cellulose or calcium hydrogen phosphate);lubricants (e.g., magnesium stearate, talc or silica); disintegrants(e.g., potato starch or sodium starch glycolate); or wetting agents(e.g., sodium lauryl sulphate). The tablets may be coated by methodswell-known in the art.

Preparations for oral administration may be suitably formulated to givecontrolled release of the active compound.

For buccal administration, the compositions may take the form of tabletsor lozenges formulated in conventional manner.

For administration by inhalation, the compounds for use according to thepresent invention are conveniently delivered in the form of an aerosolspray presentation from pressurized packs or a nebulizer, with the useof a suitable propellant, e.g., dichlorodifluoromethane,trichlorofluoromethane, dichlorotetrafluoroethane, carbon dioxide orother suitable gas. In the case of a pressurized aerosol the dosage unitmay be determined by providing a valve to deliver a metered amount.Capsules and cartridges of, e.g., gelatin for use in an inhaler orinsufflator may be formulated containing a powder mix of the compoundand a suitable powder base such as lactose or starch.

The compounds may be formulated for parenteral administration byinjection, e.g., by bolus injection or continuous infusion. Suchformulations are sterile. Formulations for injection may be presented inunit dosage form, e.g., in ampules or in multi-dose containers, with anadded preservative. The compositions may take such forms as suspensions,solutions or emulsions in oily or aqueous vehicles, and may containformulatory agents such as suspending, stabilizing and/or dispersingagents. Alternatively, the active ingredient may be in powder form forconstitution with a suitable vehicle, e.g., sterile pyrogen-free water,before use.

The compounds may also be formulated in rectal compositions such assuppositories or retention enemas, e.g., containing conventionalsuppository bases such as cocoa butter or other glycerides.

In addition to the formulations described previously, the compounds mayalso be formulated as a depot preparation. Such long acting formulationsmay be administered by implantation (for example, subcutaneously orintramuscularly) or by intramuscular injection. Thus, for example, thecompounds may be formulated with suitable polymeric or hydrophobicmaterials (for example, as an emulsion in an acceptable oil) or ionexchange resins, or as sparingly soluble derivatives, for example, as asparingly soluble salt. Liposomes and emulsions are well known examplesof delivery vehicles or carriers for hydrophilic drugs.

The compositions may, if desired, be presented in a pack or dispenserdevice which may contain one or more unit dosage forms containing theactive ingredient. The pack may for example comprise metal or plasticfoil, such as a blister pack. The pack or dispenser device may beaccompanied by instructions for administration.

The invention also provides kits for carrying out the therapeuticregimens of the invention. Such kits comprise in one or more containersof therapeutically effective amounts of the arsenic compounds inpharmaceutically acceptable form. The arsenic compound in a vial of akit of the invention may be in the form of a pharmaceutically acceptablesolution, e.g., in combination with sterile saline, dextrose solution,or buffered solution, or other pharmaceutically acceptable sterilefluid. Alternatively, the complex may be lyophilized or desiccated; inthis instance, the kit optionally further comprises in a container apharmaceutically acceptable solution (e.g., saline, dextrose solution,etc.), preferably sterile, to reconstitute the complex to form asolution for injection purposes. The kit may also include anothertherapeutic agent(s) for the treatment of pain and/or inflammation in anappropriate amount. Such other therapeutic agent may be formulated as acombination drug with the arsenic compound contained in the kit, or maybe formulated separately.

In another embodiment, a kit of the invention further comprises a needleor syringe, preferably packaged in sterile form, for injecting thecomplex, and/or a packaged alcohol pad. Instructions are optionallyincluded for administration of arsenic compounds by a clinician or bythe patient.

The magnitude of a therapeutic dose of an arsenic compound in the acuteor chronic management of pain and/or inflammation will vary with theseverity of the condition to be treated and the route of administration.The dose, and perhaps dose frequency, will also vary according to theage, body weight, condition and response of the individual patient. Ingeneral, the total daily dose ranges for the conditions described hereinare generally from about 10 μg to about 200 mg administered in divideddoses administered parenterally or orally or topically. A preferredtotal daily dose is from about 0.5 mg/kg to about 70 mg/kg of the activeingredient; and most preferably about 10 mg/kg.

Effective dosage achieved in one animal may be converted for use inanother animal, including humans, using conversion factors known in theart. See, e.g., Freireich et al., Cancer Chemother. Reports50(4):219-244 (1966) and Table 1 for equivalent surface area dosagefactors.

TABLE 1 From: Mouse Rat Monkey Dog Human To: (20 g) (150 g) (3.5 kg) (8kg) (60 kg) Mouse 1 0.5 0.25 0.17 0.08 (20 g) Rat 2 1 0.5 0.25 0.14 (150g) Monkey 4 2 1 0.6 0.33 (3.5 kg) Dog 6 4 1.7 1 0.5 (8 kg) Human 12 7 32 1 (60 kg)

Desirable blood levels may be maintained by a continuous infusion of anarsenic compound as ascertained by plasma levels. It should be notedthat the attending physician would know how to and when to terminate,interrupt or adjust therapy to lower dosage due to toxicity, or bonemarrow, liver or kidney dysfunctions. Conversely, the attendingphysician would also know how to and when to adjust treatment to higherlevels if the clinical response is not adequate (precluding toxic sideeffects).

Again, any suitable route of administration may be employed forproviding the patient with an effective dosage of an arsenic compound.For example, oral, rectal, vaginal, transdermal, parenteral(subcutaneous, intramuscular, intrathecal and the like) may be employed.Dosage forms include tablets, troches, cachet, dispersions, suspensions,solutions, capsules, patches, and the like. (See, Remington'sPharmaceutical Sciences.)

The pharmaceutical compositions of the present invention comprise anarsenic compound as the active ingredient, or apharmaceutically-acceptable salt thereof, and may also contain apharmaceutically acceptable carrier, and optionally, other therapeuticingredients, for example conventional medications for pain therapy. Theterm “pharmaceutically acceptable salts” refers to salts prepared frompharmaceutically acceptable non-toxic acids and bases, includinginorganic and organic acids and bases.

The pharmaceutical compositions include compositions suitable for oral,rectal, mucosal routes, transdermal, parenteral (including subcutaneous,intramuscular, intrathecal and intravenous), although the most suitableroute in any given case will depend on the nature and severity of thecondition being treated.

In the case where an intravenous injection or infusion composition isemployed, a suitable dosage range for use is, e.g., from about 0.5 mg toabout 150 mg total daily dose.

In addition, the arsenic carrier could be delivered via charged anduncharged matrices used as drug delivery devices such as celluloseacetate membranes, also through targeted delivery systems such asfusogenic liposomes attached to antibodies or specific antigens.

In practical use, an arsenic compound can be combined as the activeingredient in intimate admixture with a pharmaceutical carrier accordingto conventional pharmaceutical compounding techniques. The carrier maytake a wide variety of forms depending on the form of preparationdesired for administration, e.g., oral or parenteral (including tablets,capsules, powders, intravenous injections or infusions). In preparingthe compositions for oral dosage form any of the usual pharmaceuticalmedia may be employed, e.g., water, glycols, oils, alcohols, flavoringagents, preservatives, coloring agents, and the like; in the case oforal liquid preparations, e.g., suspensions, solutions, elixirs,liposomes and aerosols; starches, sugars, micro-crystalline cellulose,diluents, granulating agents, lubricants, binders, disintegratingagents, and the like in the case of oral solid preparations e.g.,powders, capsules, and tablets. In preparing the compositions forparenteral dosage form, such as intravenous injection or infusion,similar pharmaceutical media may be employed, e.g., water, glycols,oils, buffers, sugar, preservatives and the like know to those skilledin the art. Examples of such parenteral compositions include, but arenot limited to Dextrose 5% w/v, normal saline or other solutions. Thetotal dose of the arsenic compound may be administered in a vial ofintravenous fluid, e.g., ranging from about 2 ml to about 2000 ml. Thevolume of dilution fluid will vary according the total doseadministered.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein.

EXAMPLES Example 1 Use of Animal Models to Test Analgesic Activity

Animal models for chemical-induced pain were used to determine theanalgesic activity of various concentrations of sodium meta arsenite andarsenic trioxide.

Mouse Formalin Test. Sodium meta arsenite or arsenic trioxide wasadministered orally (PO) or intraperitoneally (IP), respectively, togroups of ten CD-1 (Crl.) derived male mice weighing 24+/−2 g. Sodiummeta arsenite and vehicle (distilled water) or arsenic trioxide andvehicle were each administered one hour before subplantar injection offormalin 0.02 ml, 2% solution). Reduction of the formalin-induced hindpaw licking time recorded at five minute intervals during the following0 to 35 minute period after formalin injection by 50% or more (≧50%)indicated significant analgesic activity. Statistical analysis wasperformed using One-way ANOVA followed by Dunnett's test for comparingresults obtained with sodium meta arsenite or arsenic trioxide to thoseobtained with vehicle (control) alone. Significance was considered atP<0.05. The results are summarized below:

Sodium Meta Arsenite Hind paw licking time (Seconds) (Mean ± SEM) DoseTime (minutes) Treatment Route mg/kg 0-5 5-10 10-15 15-20 20-25 25-3030-35 Vehicle PO- — 66.7 ± 6.4 0.9 ± 0.9 10.1 ± 4.3  81.7 ± 20.7 72.4 ±25.4 30.8 ± 10.1  4.8 ± 10.6 SMA PO 10 51.2 ± 5.2 0.1 ± 0.1 4.7 ± 4.66.5* ± 4.5  20.5 ± 10.8 29.2 ± 7.6  6.6 ± 4.2 SMA PO 1 54.9 ± 6.3 2.7 ±1.8 7.6 ± 2.8 44.6 ± 13.5 55.7 ± 13.9 45.0 ± 19.3 21.3 ± 9.7  SMA PO 0.176.1 ± 8.6 4.3 ± 4.2 24.0 ± 10.4 69.4 ± 13.0 46.0 ± 11.8 44.6 ± 13.0 4.9± 1.8 Morphine PO 30 20.8 ± 3.6 0.1 ± 0.1 2.01.8 2.0* ± 2.0  10.4* ±8.2  16.2 ± 8.4  3.3 ± 1.8 SMA: sodium meta arsenite *P < 0.05 versusthe vehicle control group

The results indicate that oral administration of sodium meta arsenite at10 mg/kg caused significant analgesic activity at 15-20 minutes afterformalin challenge. The standard, morphine, caused significant analgesiceffect during the early (0-5 minutes) and late (15-25 minutes) phasesafter formalin injection, as expected.

Arsenic Trioxide Hind paw licking time (Seconds) (Mean ± SEM) Time(minutes) Treatment Route Dose mg/kg 0-5 5-10 10-15 15-20 20-25 25-3030-35 Vehicle IP-  5 ml/kg X 78.9 8.5 40.5 58.7 78.8 61.3 20.7 SEM 6.82.7 10.5 18.8 15.0 20.2 12.4 AT IP 10 mg/kg X 9.0* 0.3* 0.0* 0.0* 0.0*0.0* 0.0 SEM 6.3 0.3 0.0 0.0 0.0 0.0 0.0 AT IP  1 mg/kg X 74.6 2.6*15.6* 40.0 57.1 53.5 30.0 SEM 11.3 1.5 5.5 13.3 18.1 15.3 18.8 MorphineIP 10 mg/kg X 29.7* 0.0* 0.7* 3.3* 22.8* 30.1 40.8 SEM 5.2 0.0 0.7 1.713.8 6.4 11.5 AT: Arsenic Trioxide *P < 0.05 versus the vehicle controlgroup using one-way ANOVA followed by Dunnett's test

Intraperitoneal injection of arsenic trioxide at 10 mg/kg causedsignificant inhibition of the licking response to formalin challenge atthe intervals of 0-5, 5-10, 10-15, 15-20, 20-25 and 25-30 minutes afterformalin challenge, whereas response to the lower dose of arsenictrioxide (1 mg/kg) was limited to the intervals of 5-10 and 10-15minutes after challenge. Concurrently run standard morphine HCl wasassociated with analgesic effect at 0-25 minutes after formalinchallenge.

Acetic Acid-Induced Pain Response Assay. Sodium meta arsenite wasevaluated for possible analgesic activity in the mouse aceticacid-induced pain response assay. Sodium meta arsenite was administeredorally at doses of 10, 1 and 0.1 mg/kg for possible analgesia in themouse. Distilled water was used as vehicle. One hour before injection ofacetic acid (0.5%, 20 ml/kg IP), sodium meta arsenite was administeredorally to groups of 10 CD-1 derived male mice, weighing 24±2 g.Significant analgesic activity was defined as a reduction in number ofwrithing responses by 50% or more (≧50%) relative to control groups at5-10 minutes after acetic acid administration.

Administration of 10 mg/kg sodium meta arsenite was associated withsignificant analgesic activity (average 7 writhing events versus 16 forcontrol). At lower doses sodium meta arsenite had no analgesic effect.

Example 2 Use of Animal Models to Test Anti-Inflammatory Activity ofSodium Meta Arsenite and Arsenic Trioxide

Sodium meta arsenite and arsenic trioxide were tested for possibleprotective effects against lipopolysaccharide-induced septic shock inmice.

LPS-Induced Pro-inflammatory Cytokine Production. Sodium meta arsenitewas administered orally at 0.1, 1 and 10 mg/kg doses, one hour prior tochallenge with lipopolysaccharide (LPS; 30 mg/kg IP; Escherechia coli055:B5). Two hours after LPS challenge, 0.1 ml blood samples were takenfrom the mice via the retro-orbital and centrifuged to yield plasma forcytokine measurements by Luminex. After blood collection, mortality wasmonitored and recorded every 12 hours over a 3-day period. Reduction inmortality by 50 percent or more (≧50%) indicates significant protection.The results are shown in the table below:

Sodium Meta Arsenite:

Route Dose % Protection PO  10 mg/kg 25 PO 1.0 mg/kg 25 PO 0.1 mg/kg 12Dexamehasone 21-acetate PO  3. mg/kg (75)

The results show that sodium meta arsenite at doses of 0.1, 1.0, and 10mg/kg PO afforded moderate protection against LPS-induced septic shockin mice. A significant inhibition of IL-1β secretion at 1 and 10 mg/kgPO sodium meta arsenite and inhibition of IL-6 (versus dexamethasone at3 mg/kg) at 10 mg/kg were also observed. Sodium meta arsenite had noeffect on secretion of TNF-α, KC or MCP-1.

LPS-Induced Neutrophilia in Lung Tissue. Sodium meta arsenite wasevaluated for possible protective activity in a mouse model ofLPS-induced neutrophilia in lung tissues. Sodium meta arsenite at dosesof 0.1, 1 and 10 mg/kg was administered orally (PO) two hours beforechallenge with LPS. Twenty-four hours after LPS challenge, brachoaveolarlavage fluid was harvested from individual animals for total anddifferential cell counts.

Sodium meta arsenite at 10 mg/kg PO was not associated with anysignificant changes in cell counts. However, at 1 mg/kg a significantdecrease in white blood cell (total) and neutrophil (differential) andmonocyte counts versus vehicle control treated with LPS were observed.

Dexamethasone at 1 mg/kg PO afforded significant protection in terms ofsuppression of total white blood cell, as well as differentialneutrophil and monocyte counts relative to control.

At 10 mg/kg, but not 1 or 0.1 mg/kg, administration of sodium metaarsenite correlated with a significant suppression of TNF-α similar todexamethasone, the standard. At 1 mg/kg, but not 0.1 mg/kg or 10 mg/kg,administration of sodium meta arsenite correlated with significantreduction in KC similar to dexamethasone. The KC effect did not appearto be dose-related. At no concentration of sodium meta arsenite wassecretion of IL-1β, Il-6 or MCP-1 observed in brachoaveolar lavagefluid.

Example 3 Immunosuppression Studies

Hyperplasia of popliteal lymph nodes (PLN) has been used as a dependableindicator of lymphatic system reaction in host-versus-graft studies. Theheterotropic heart transplantation model in the rat has been usedsuccessfully to evaluate immunosuppressive agents. A combination of PLNhyperplasia assay and heart transplantation model was used to obtaininformation relating to the efficacy of host lymphocytes in bothalloreactive proliferation and allorejection. The results show thatsodium meta arsenite has immunosuppressive effects.

Heart transplantation. Donor hearts were transplanted into the recipientmouse as described (Chen et al., Transplantation, 56:661-666, 1993; Chenet al., The Journal of Immunology, 152:3107-3318, 1994). Thetransplanted donor hearts were checked every day and sodium metaarsenite was administered for two weeks or until the graft was rejected,whichever occurred first.

In the heart transplantation model, the higher dose (10 mg/kg) sodiummeta arsenite showed a slight immunosuppressive effect in animalstreated with alloantigen and an overall positive effect on thetransplant. It appears that sodium meta arsenite may compromise thereaction of host lymphocytes to alloantigen at the higher dose. Thus,the arsenic compounds of the invention are also immunosuppressiveagents.

Example 4 Type-II Collagen Induced Arthritis

Rat collagen arthritis is an experimental model of polyarthritis thathas been widely used for preclinical testing of numerous anti-arthriticagents that are either under preclinical or clinical investigation orare currently used as therapeutics in this disease. The hallmarks ofthis model are reliable onset and progression of robust, easilymeasurable, polyarticular inflammation, marked cartilage destructionwith pannus formation and mild to moderate bone resorption andperiosteal bone proliferation. Therapeutic agents that inhibit Il-1production or activity are especially active in this test system, butother types of anti-inflammatory agents have good to excellent activity.

This study was undertaken to determine the dose responsive oral (PO)efficacy of sodium meta arsenite and intraperitoneal (IP) efficacy ofarsenic trioxide, respectively, administered daily for inhibition of theinflammation (paw swelling), cartilage destruction and bone resorptionthat occurs in developing type II collagen arthritis in rats.

Animals (8 per group, 4 per group for normals) were anesthetized withIsoflurane and injected with 300 μl Freund's incomplete adjuvant (Difco,Detroit, Mich.) containing 2 mg/mL bovine type II collagen. (Elastinproducts, Owensville, Mo.) at the base of the tail and two sites on theback on days 0 and 6. Dosing by IP or oral route (QD at 24 hourintervals) was initiated on day 0 of the study and continued through day16. Experimental groups were as follows:

Sodium Meta Arsenite:

Group N Treatment: Oral, QD days 0-16, 5 ml/kg 1 4 Normal controls pluswater 2 10 Arthritis plus water 3 10 Arthritis plus sodium meta arsenite10 mg/kg 4 10 Arthritis plus sodium meta arsenite 5 mg/kg 5 10 Arthritisplus sodium meta arsenite 0.1 mg/kg 6 10 Arthritis plus MTX 0.075 mg/kg

Arsenic Trioxide:

Group N QD Treatment day 0-16, 10 ml/kg IP groups 1-4 1 4 Normalcontrols plus vehicle IP 2 8 Arthritis plus vehicle 3 8 Arthritis plusarsenic trioxide 10 mg/kg IP 4 8 Arthritis plus arsenic trioxide 1 mg/kgIP 5 8 Arthritis plus arsenic trioxide 10 mg/kg PO (5 ml/kg)

Rats were weighed on days 0, 3, 6, 9-17 of the study and calipermeasurements of ankles were taken every day beginning on day 9 (or day 0of arthritis). After final body weight measurement on day 17, animalswere anesthetized for serum and then euthanized for tissue collection.Hind paws were transected at the level of the medial and lateralmalleolus, weighed and placed in formalin, with knees, for microscopy.Liver, spleen and thymus were removed from each animal, weighed anddiscarded.

A PK sampling was done on days 16 using 6 animals per group (arthritic)as follows: animals 1, 2, 3 were bled for pre-dose, 2 and 8 hoursamples; animals 6, 7 and 8 were bled for 1, 4 and 12 hour post-dosesamples.

Morphologic pathology of the sodium meta arsenite-treated rats wasundertaken, but none was conducted for the arsenic trioxide-treatedanimals. For these tests, preserved and decalcified ankle and kneejoints were cut in half longitudinally (ankles) or in the frontal plane(knees), processed through graded alcohols and a clearing agent,infiltrated and embedded in paraffin, sectioned and stained withToluidine Blue. All tissues were examined microscopically by a boardcertified veterinary pathologist.

Collagen arthritic ankles and knees were given scores of 0-5 (0=normal;5=severe) for inflammation, pannus formation and bone resorption.Statistical analysis of body/paw weights, paw AUC (area under the curve)parameters and histopathologic parameters were evaluated using aStudent's t-test with significance set at the 5% significance level.

Percent inhibition of paw weight and AUC was calculated using thefollowing formula:

% inhibition=A−B/A×100

A=Mean Disease Control−Mean Normal

B=Mean Treated−Mean Normal

Results: Sodium Meta Arsenite: Body weight loss (due to arthritis) wassignificantly inhibited by treatment with 10 mg/kg sodium meta arsenite(100% inhibition), or MTX (96%), as compared to vehicle treated diseasecontrol rats. Calculated ED₅₀ value=1.929 mg/kg.

Significant inhibition of ankle diameter was seen in rats treated with10 mg/kg sodium meta arsenite (days 9, 11-17) or MTX (days 10-17).

Inhibition of ankle diameter (AUC) was significant for rats treated with10 mg/kg sodium meta arsenite (73% inhibition), or MTX (97%), ascompared to disease controls. Calculated ED₅₀ value=8.499 mg/kg.

Inhibition of final paw weight was significant for rats treated with 10mg/kg sodium meta arsenite (83%), or MTX (95%), as compared to diseasecontrols. Calculated ED₅₀ value=7.116 mg/kg.

Relative liver weights were increased, above normal and arthriticcontrols for rats treated with 10 mg/kg sodium meta arsenite (17%increase over disease controls).

Relative spleen weights were reduced by treatment with 10 mg/kg sodiummeta arsenite (10%), or MTX (10%), as compared to disease control rats.Relative thymus weights were significantly reduced in rats treated with1 mg/kg sodium meta arsenite (20%), as compared to disease controls.

All vehicle treated disease control rats had marked to severe synovitisand periarticular inflammation in at least one, and usually both, anklejoints with minimal to moderate pannus and bone resorption, and minimalto marked cartilage damage. In contrast, all ankle histopathologyparameters were significantly inhibited to normal in rats treated with10 mg/kg sodium meta arsenite (85%) inhibition, or MTX (97%). CalculatedED₅₀ value=7.080 mg/kg.

All ten vehicle treated disease control rats had moderate to severesynovitis and periarticular inflammation in at least one knee joint withminimal to moderate pannus and bone resorption, and cartilage damage. Incontrast, knee histopathologic parameters were significantly inhibitedtoward normal in rats treated with 10 mg/kg sodium meta arsenite (87%inhibition), or MTX (100%). Calculated ED₅₀ value=7.924 mg/kg.

The results obtained from this study indicate that oral, daily treatmentof rats with 10 mg/kg sodium meta arsenite effectively inhibits theclinical and histopathological changes associated with developing typeII collagen arthritis.

Results: Arsenic Trioxide and Sodium Meta Arsenite: Body weight loss wassignificantly inhibited by IP, QD treatment with 10 mg/kg arsenictrioxide (55% inhibition), or PO, QD treatment with 10 mg/kg sodium metaarsenite (85%), as compared to vehicle treated disease control rats.

Significant inhibition of decrease in ankle diameter was seen in ratstreated with 10 mg/kg arsenic trioxide (days 10-17), or 10 mg/kg sodiummeta arsenite (days 11-17). Inhibition of ankle diameter AUC wassignificant for rats treated IP, QD with 10 mg/kg arsenic trioxide (80%inhibition); and PO, QD with 10 mg/kg sodium meta arsenite (66%), ascompared to disease controls.

Inhibition of final paw weight was significant for rats treated IP, QDwith 10 mg/kg arsenic trioxide (71% inhibition), or PO, QD with 10 mg/kgsodium meta arsenite (69%), as compared to disease controls.

Relative liver weights were increased above arthritic controls for ratstreated with 1 or 10 mg/kg arsenic trioxide (6% and 10%, respectively),or 10 mg/kg sodium meta arsenite (14%).

Relative spleen weights were reduced, below normal and arthriticcontrols, by treatment with 10 mg/kg arsenic trioxide (21%) or 10 mg/kgsodium meta arsenite (10%), as compared to disease control rats.Relative thymus weights were reduced below arthritic controls in ratstreated with 10 mg/kg arsenic trioxide.

The results of this study indicate that intraperitoneal, daily treatmentof rats with 10 mg/kg arsenic trioxide, or oral, daily treatment with 10mg/kg sodium meta arsenite effectively inhibits clinical changesassociate with developing type II collagen arthritis.

Example 5 Adjuvant Induced Arthritis

This study was undertaken to evaluate the efficacy of sodium metaarsenite (PO, QD days 0-13) in inhibiting periarticular inflammation andbone resorption of established adjuvant arthritis. Rat adjuvantarthritis is an experimental model of polyarthritis that has been widelyused for preclinical testing of numerous anti-arthritic agents. Thehallmarks of this model are reliable onset and progression of robust,easily measurable, polyarticular inflammation, marked bone resorptionand periosteal bone proliferation. Cartilage destruction occurs, but isdisproportionately mild in comparison to the inflammation and bonedestruction that occurs. Use of the adjuvant model provides anopportunity to study pathologic changes in a variety of tissues otherthan the joints.

Animals were randomly assigned to groups (8 per group for adjuvant, 4per group for normal controls) and anesthetized with Isoflurane andinjected with 100 μl Freund's complete Adjuvant (Sigma, St. Louis, Mo.)containing lipoidal amine (60 mg/ml) at the base of the tail on day 0.Dosing by the PO route was initiated on day 0 (prophylactic treatment)with vehicle (water), sodium meta arsenite (3, 10, or 30 mg/kg) ormethotrexate (MTX) (0.1 mg/kg). Treatment continued until day 13.Experimental groups were as follows:

Group N Treatment: PO, QD days 0-13, 1 4 Normal controls plus water 2 8Adjuvant plus water 3 8 Adjuvant plus sodium meta arsenite 30 mg/kg 4 8Adjuvant plus sodium meta arsenite 10 mg/kg 5 8 Adjuvant plus sodiummeta arsenite 3 mg/kg 6 8 Adjuvant plus MTX 0.1 mg/kg

Rats were weighed on days 0, 4 and 8-13 at which times dose volumes wereadjusted. On day 7 (prior to swelling onset, but after establishment ofsystemic disease), caliper measurements were made of ankle joints.Ankles were measured again on days 8-14. Final body weights were takenon day 14. On day 14, animals were euthanized and hind paws, liver andspleen were removed and weighed. Paws and spleen were placed in formalinand processed for H&E and microscopy.

Adjuvant arthritic ankles (right only) were given scores of 0-5(0=normal; 5=severe) for inflammation and bone resorption. Statisticalanalysis of ankle joint diameter was analyzed by determining the areaunder the dosing curve (AUC). For calculation of AUC, the dailymeasurement of ankle joints (using a caliper) for each rat were enteredinto Microsoft Excel where the area between the treatment days after theonset of disease to the termination day was computed. Means for eachgroup were determined and % inhibition for arthritis controls wascalculated by comparing values for treated and normal animals. Pawweights, spleen and liver weights and histology parameters (mean ±SE)for each group were analyzed for differences using the Student's t testor other appropriate analysis as determined after seeing the data. Inboth cases, significance was set at p≦0.05.

Percent inhibition of paw weight and AUC was calculated using thefollowing formula:

% inhibition=A−B/A×100

A=Mean Disease Control−Mean Normal

B=Mean Treated−Mean Normal

ED₅₀ calculations were done by plotting the % inhibition versus thenatural log of the dose concentration and generating a sigmoidaldose-response curve (variable slope). The zero concentration dose(vehicle group) was incorporated into the graph by assigning it a dosevalue of 2 log units lower than the lowest dose given. Constraints ofthe curve were set at 0 and 100%. Software was used to generate anequation for the curve and calculated the concentration at which animalswould show 50% inhibition of the parameter (ED₅₀).

Results. Mean body weight decrease over time (due to arthritis) wasinhibited in rats treated PO with 0.1 mg/kg MTX (significant days10-14), as compared to vehicle treated control rats. Mean body weightloss over time was significantly increased in rats treated with 30 mg/kgsodium meta arsenite (days 4, 8, 9), as compared to the vehiclecontrols.

Inhibition of body weight loss from day zero was significant for ratstreated with 0.1 mg/kg MTX (91% inhibition). Body weight loss from day 0was non-significantly (2-14%) inhibited by treatment with sodium metaarsenite (3, 10 and 30 mg/kg), as compared to the vehicle controls.

Significant inhibition of ankle diameter increase was observed in ratstreated PO with 3 mg/kg sodium meta arsenite (significant day 9), 10mg/kg sodium meta arsenite (significant days 8-14), 30 mg/kg sodium metaarsenite (significant days 8-14), and 0.1 mg/kg MTX (significant days8-14), as compared to vehicle controls.

Significant and dose responsive inhibition of ankle diameter AUCincrease was observed in rats treated PO with 10 mg/kg sodium metaarsenite (46% inhibition), 30 mg/kg sodium meta arsenite (83%inhibition) and 0.1 mg/kg MTX (96% inhibition), as compared to vehiclecontrols. Calculated ED₅₀ for sodium meta arsenite=10.62 mg/kg.

Final paw weight increase due to arthritis was significantly anddose-responsively inhibited in animals treated PO with 10 mg/kg sodiummeta arsenite (28% inhibition), 30 mg/kg sodium meta arsenite (83%inhibition), and 0.1 mg/kg MTX (99% inhibition), as compared to vehiclecontrols. Calculated ED₅₀ for sodium meta arsenite=14.21 mg/kg.

Relative spleen weights (increased due to inflammation and enhancedextramedullary hematopoiesis) were significantly and dose-responsivelyreduced toward normal in rats treated PO with 10 mg/kg sodium metaarsenite (50% reduction), 30 mg/kg sodium meta arsenite (91% reduction),and 0.01 MT (77% reduction), as compared to vehicle controls.

Relative liver weights were significantly reduced toward normal in ratstreated with MTX (100% reduction). Relative liver weights werenon-significantly reduced (7-29%) by treatment with sodium meta arsenite(3, 10 and 30 mg/kg).

Histopathologic bone resorption was significantly and dose-responsivelyinhibited in rats treated PO with 10 mg/kg sodium meta arsenite (59%inhibition), 30 mg/kg sodium meta arsenite (81% inhibition), and 0.1mg/kg MTX (100% inhibition), as compared to vehicle controls. CalculatedED₅₀ for sodium meta arsenite=9.243 mg/kg.

Significant and dose-responsive inhibition of histopathologicinflammation as compared to the vehicle controls was observed in ratstreated PO with 10 mg/kg sodium meta arsenite (24% inhibition), 30 gm/kgsodium meta arsenite (76% inhibition) and 0.1 mg/kg MTX (99%inhibition). Calculated ED₅₀ for sodium meta arsenite=17.25 mg/kg.

Ankle measurements (dorsal to ventral) were significantly anddose-responsively inhibited by treatment with 10 mg/kg sodium metaarsenite (36% inhibition), 30 mg/kg sodium meta arsenite (81%inhibition) and 0.1 mg/kg MTX (97% inhibition), as compared to vehiclecontrols. Calculated ED₅₀ for sodium meta arsenite=13.65 mg/kg.

Splenic inflammation and lymphoid atrophy were significantly anddose-responsively inhibited in rats receiving 10/kg sodium meta arsenite(32% and 29% inhibition, respectively), 30 mg/kg sodium meta arsenite(89% and 39% inhibition, respectively) and 0.1 mg/kg MTX (100% and 50%inhibition, respectively), as compared to vehicle controls.

Results of this study indicate that oral (PO) treatment with 10 mg/kg(QD), or 30 mg/kg (QD2) sodium meta arsenite effectively anddose-responsively inhibits the clinical and histopathological changesassociated with developing adjuvant arthritis. A daily dose of 30 mg/kgsodium meta arsenite was toxic (based on body weight changes), but everyother dat dosing during the active phase of the disease was welltolerated and body weights then tracked with disease controls from day10 to study termination.

Example 6 Treatment of Tumor Induced Osteolysis with Sodium MetaArsenite

In this study, a candidate therapy for treatment of tumor-induced boneosteolysis, sodium meta arsenite, was evaluated using a syngeneic ratmodel of bone cancer. In brief, the rat mammary gland carcinoma cellline, MRMT-1, was injected into the marrow space of the proximal tibiaon Day 1 and the animals were dosed by oral gavage with vehicle sodiummeta arsenite once daily from Days 1-14. Morphine was used as areference article and was dosed just prior to behavioral testing. At theconclusion of the experimental period, the left tibiae were excised forradiographic confirmation of tumor osteolysis. Radiographs were used toselect two representative bones from each group for micro-CT scanning.All bone samples were decalcified for TRAP staining and evaluation ofosteoclastic activity (resorbing surfaces) and for histopathologicalassessment of bone structure and tumor burden. Sodium meta arseniteefficacy was based on a comparison with the tumor-inoculated,vehicle-treated group.

The histopathological results showed that at the dose level of 10 mg/kgsodium meta arsenite demonstrated a positive trend on improving thevarious aspects of cancer-induced bone damage. The data show that at 10mg/kg sodium meta arsenite had a strong positive trend towardameliorating tumor-induced osteoclasts and osteolysis. The data areshown in FIG. 1.

Example 7 Pharmacokinetic Profile of Sodium Meta Arsenite Following Oraland I.V Administration

Plasma and brain pharmacokinetic profiles following oral (PO) andintravenous (IV) administration of sodium meta arsenite in male CD-1mice were determined. Seventy three male CD-1 (ICR) albino mice(approximately four weeks old, 18-27 g upon start of testing) wererandomly assigned to treatment groups. Animals were fasted for two hoursprior to administration of test drug. The animals were treated with 10mg/kg (PO) or 5 mg/kg (IV), with a target dose volume of 10 mL/kg.Following administration, blood samples (0.2 to 0.3 mL) were obtainedvia the vena cava under isoflurane anesthesia at 5, 15, 30, 60, 120,240, 480, 14490, 1920, 2880, 3360, and 4320 minutes post-dose.Immediately following each blood collection, the animals were sacrificedand the brain collected at 5, 30, 60, 120, 240, 480, 1440, 2880 and 4320minutes post-dose.

The plasma and whole brain samples were digested with concentratednitric acid in a Teflon bomb at 105° C. The digestate was diluted to 40mL for analysis by ICP-MS. The digestate was aspirated into theinductively coupled Plasma and the resulting ions were extracted by avacuum interface into a quadruple mass analyzer. The amount of arsenicin the samples was measured by comparison t response at a standardsolution of mass 75. NRCC-DOLT-3 and DORM-2 were analyzed as standardreference materials.

The study sample concentration versus data was analyzed to generate thefollowing PK parameters by noncompartmental analysis (WinNonlin, version2.1):

Parameter Units Notes T_(max) Hour Time to reach maximum concentrationC_(max) Ng/mL Highest concentration within the timeframe AUC_(all) Ng ·hr/mL Area under the curve, generated by log-linear trapezoidal methodfor interpolation F % % Bioavailability of orally dosed animals

The results are set forth in the tables below:

Plasma PK Results: Sodium Meta Arsenite (PO, 10 mg/kg) Pharmacokinetic(PK) Parameter Units PK Results (N = 3) AUC_(all) mg * hr/Kg 6.85C_(max) Mg/Kg 0.52 T_(max) Hr 4 F % % 101% Pharmacokinetic analysiscompleted using the mean (N = 3) concentration value at each collectiontimepoint.

Plasma PK Results: Sodium Meta Arsenite (IV, 5 mg/kg) Pharmacokinetic(PK) Parameter Units PK Results (N = 3) AUC_(all) mg * hr/Kg 3.38C_(max) Mg/Kg 0.41 T_(max) Hr 0.25 F % % N/A Pharmacokinetic analysiscompleted using the mean (N = 3) concentration value at each collectiontimepoint. N/A: Not applicable

Brain PK Results: Sodium Meta Arsenite (PO, 10 mg/kg Pharmacokinetic(PK) Parameter Units PK Results (N = 3) AUC_(all) mg * hr/Kg 6.73C_(max) Mg/Kg 0.33 T_(max) Hr 8 F % % 87% Pharmacokinetic analysiscompleted using the mean (N = 3) concentration value at each collectiontime point.

Brain PK Results: Sodium Met \a Arsenite (IV 5 mg/kg Pharmacokinetic(PK) Parameter Units PK Results (N = 3) AUC_(all) mg * hr/Kg 3.86C_(max) Mg/Kg 0.32 T_(max) Hr 4 F % % N/A Pharmacokinetic analysiscompleted using the mean (N = 3) concentration value at each collectiontimepoint. N/A: Not applicable

1. A method for treating pain in a mammal comprising administering tothe mammal a therapeutically effective amount of an arsenic compoundselected from sodium meta arsenite, arsenic trioxide, arsenic hexoxideand combinations thereof.
 2. The method of claim 2 wherein the arseniccompound is sodium meta arsenite.
 3. The method of claim 2 wherein thearsenic compound is arsenic trioxide.
 4. The method of claim 1 whereinthe arsenic compound is a combination of sodium meta arsenite andarsenic trioxide.
 5. The method of claim 1 wherein the pain is visceralpain, post-surgical pain, central pain, chronic pain, or spinal pain. 6.The method of claim 1 wherein the arsenic compound is administered tothe mammal at an amount of from about 0.5 mg/kg to about 70 mg/kg.
 7. Amethod of treating inflammation in a mammal comprising administering tothe mammal a therapeutically effective amount of an arsenic compoundselected from sodium meta arsenite, arsenic trioxide and arsenichexoxide.
 8. The method of claim 8 wherein the inflammation isassociated with asthma.
 9. The method of claim 8 wherein theinflammation is chronic obstructive pulmonary disease.
 10. The method ofclaim 8 wherein the inflammation is associated with autoimmune disease.11. The method of claim 8 wherein the arsenic compound is administeredtopically to relieve local inflammation.
 12. The method of claim 8wherein the inflammation is associated with arthritis.
 13. The method ofclaim 8 wherein the arsenic compound is sodium meta arsenite.
 14. Themethod of claim 8 wherein the arsenic compound is arsenic trioxide. 15.The method of claim 14 wherein the therapeutically effective amount isin the range of from about 0.5 mg/kg to 70 mg/kg.
 16. The method ofclaim 14 wherein the arsenic compound is administered orally.
 17. Amethod of treating tumor-induced osteolysis comprising administering toa patient in need thereof a therapeutically effective amount of sodiummeta arsenite.
 18. A kit comprising at least one therapeuticallyeffective dosage amount of a a first pain treatment agent comprising anarsenic compound selected from sodium meta arsenite, arsenic trioxide,arsenic hexoxide and combinations thereof, wherein the therapeuticallyeffective amount of the arsenic compound is sufficient to reduce orprevent pain in a target mammal, and optionally, at least onetherapeutically effective dosage amount of a second pain treatmentagent, wherein said second pain treatment agent is a non-arseniccompound.
 19. The kit according to claim 16, wherein the arseniccompound is sodium meat arsenite, arsenic trioxide or a combinationthereof.
 20. A method for treating or preventing tissue or organrejection in a mammal receiving a tissue or organ transplant comprisingadministering to the mammal a therapeutically effective amount of sodiummeta arsenite.
 21. A kit comprising at least one therapeuticallyeffective dosage amount of a a first anti-inflammatory agent comprisingan arsenic compound selected from sodium meta arsenite, arsenictrioxide, arsenic hexoxide and combinations thereof, wherein thetherapeutically effective amount of the arsenic compound is sufficientto reduce or prevent inflammation in a target mammal, and optionally, atleast one therapeutically effective dosage amount of a secondanti-inflammatory agent, wherein said second anti-inflammatory agent isnot an arsenic compound.